Rollup merge of #100590 - TaKO8Ki:suggest-adding-array-length, r=compiler-errors

Suggest adding an array length if possible

fixes #100448

src/test/ui/array-slice-vec/suggest-array-length.fixed

@@ -0,0 +1,14 @@
+// run-rustfix
+#![allow(unused_variables, dead_code, non_upper_case_globals)]
+
+fn main() {
+    const Foo: [i32; 3] = [1, 2, 3];
+    //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
+    //~| ERROR using `_` for array lengths is unstable
+    let foo: [i32; 3] = [1, 2, 3];
+    //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
+    //~| ERROR using `_` for array lengths is unstable
+    let bar: [i32; 3] = [0; 3];
+    //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
+    //~| ERROR using `_` for array lengths is unstable
+}

src/test/ui/array-slice-vec/suggest-array-length.rs

@@ -0,0 +1,14 @@
+// run-rustfix
+#![allow(unused_variables, dead_code, non_upper_case_globals)]
+
+fn main() {
+    const Foo: [i32; _] = [1, 2, 3];
+    //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
+    //~| ERROR using `_` for array lengths is unstable
+    let foo: [i32; _] = [1, 2, 3];
+    //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
+    //~| ERROR using `_` for array lengths is unstable
+    let bar: [i32; _] = [0; 3];
+    //~^ ERROR in expressions, `_` can only be used on the left-hand side of an assignment
+    //~| ERROR using `_` for array lengths is unstable
+}

src/test/ui/array-slice-vec/suggest-array-length.stderr

@@ -0,0 +1,48 @@
+error: in expressions, `_` can only be used on the left-hand side of an assignment
+  --> $DIR/suggest-array-length.rs:8:20
+   |
+LL |     let foo: [i32; _] = [1, 2, 3];
+   |                    ^ `_` not allowed here
+
+error: in expressions, `_` can only be used on the left-hand side of an assignment
+  --> $DIR/suggest-array-length.rs:11:20
+   |
+LL |     let bar: [i32; _] = [0; 3];
+   |                    ^ `_` not allowed here
+
+error: in expressions, `_` can only be used on the left-hand side of an assignment
+  --> $DIR/suggest-array-length.rs:5:22
+   |
+LL |     const Foo: [i32; _] = [1, 2, 3];
+   |                      ^ `_` not allowed here
+
+error[E0658]: using `_` for array lengths is unstable
+  --> $DIR/suggest-array-length.rs:5:22
+   |
+LL |     const Foo: [i32; _] = [1, 2, 3];
+   |                      ^ help: consider specifying the array length: `3`
+   |
+   = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
+   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
+
+error[E0658]: using `_` for array lengths is unstable
+  --> $DIR/suggest-array-length.rs:8:20
+   |
+LL |     let foo: [i32; _] = [1, 2, 3];
+   |                    ^ help: consider specifying the array length: `3`
+   |
+   = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
+   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
+
+error[E0658]: using `_` for array lengths is unstable
+  --> $DIR/suggest-array-length.rs:11:20
+   |
+LL |     let bar: [i32; _] = [0; 3];
+   |                    ^ help: consider specifying the array length: `3`
+   |
+   = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
+   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
+
+error: aborting due to 6 previous errors
+
+For more information about this error, try `rustc --explain E0658`.

src/test/ui/async-await/issues/issue-95307.stderr

@@ -9,6 +9,12 @@ LL |     async fn new() -> [u8; _];
    = note: `async` trait functions are not currently supported
    = note: consider using the `async-trait` crate: https://crates.io/crates/async-trait
 
+error: in expressions, `_` can only be used on the left-hand side of an assignment
+  --> $DIR/issue-95307.rs:7:28
+   |
+LL |     async fn new() -> [u8; _];
+   |                            ^ `_` not allowed here
+
 error[E0658]: using `_` for array lengths is unstable
   --> $DIR/issue-95307.rs:7:28
    |
@@ -18,12 +24,6 @@ LL |     async fn new() -> [u8; _];
    = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
    = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
 
-error: in expressions, `_` can only be used on the left-hand side of an assignment
-  --> $DIR/issue-95307.rs:7:28
-   |
-LL |     async fn new() -> [u8; _];
-   |                            ^ `_` not allowed here
-
 error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0658, E0706.

src/test/ui/feature-gates/feature-gate-generic_arg_infer.normal.stderr

@@ -1,33 +1,24 @@
-error[E0658]: using `_` for array lengths is unstable
-  --> $DIR/feature-gate-generic_arg_infer.rs:11:27
-   |
-LL |     let _x: [u8; 3] = [0; _];
-   |                           ^
-   |
-   = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
-   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
-
 error: in expressions, `_` can only be used on the left-hand side of an assignment
   --> $DIR/feature-gate-generic_arg_infer.rs:11:27
    |
 LL |     let _x: [u8; 3] = [0; _];
    |                           ^ `_` not allowed here
 
-error[E0658]: using `_` for array lengths is unstable
-  --> $DIR/feature-gate-generic_arg_infer.rs:14:18
-   |
-LL |     let _y: [u8; _] = [0; 3];
-   |                  ^
-   |
-   = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
-   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
-
 error: in expressions, `_` can only be used on the left-hand side of an assignment
   --> $DIR/feature-gate-generic_arg_infer.rs:14:18
    |
 LL |     let _y: [u8; _] = [0; 3];
    |                  ^ `_` not allowed here
 
+error[E0658]: using `_` for array lengths is unstable
+  --> $DIR/feature-gate-generic_arg_infer.rs:14:18
+   |
+LL |     let _y: [u8; _] = [0; 3];
+   |                  ^ help: consider specifying the array length: `3`
+   |
+   = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
+   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
+
 error[E0747]: type provided when a constant was expected
   --> $DIR/feature-gate-generic_arg_infer.rs:20:20
    |
@@ -37,6 +28,15 @@ LL |     let _x = foo::<_>([1,2]);
    = help: const arguments cannot yet be inferred with `_`
    = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
 
+error[E0658]: using `_` for array lengths is unstable
+  --> $DIR/feature-gate-generic_arg_infer.rs:11:27
+   |
+LL |     let _x: [u8; 3] = [0; _];
+   |                           ^
+   |
+   = note: see issue #85077 <https://github.com/rust-lang/rust/issues/85077> for more information
+   = help: add `#![feature(generic_arg_infer)]` to the crate attributes to enable
+
 error: aborting due to 5 previous errors
 
 Some errors have detailed explanations: E0658, E0747.